1. Field of the Invention
The present invention relates to an image correction apparatus, an overhead image reading apparatus, an image correction method, and a program.
2. Description of the Related Art
There are conventionally various types of image reading apparatuses for reading an image of a document and electrically processing the same. For example, there is an image reading apparatus which two-dimensionally reads the image by moving a reading range in a sub-scanning direction while carrying out reading by a one-dimensional image sensor. There also provided are some image reading apparatuses which read the document under an environment an environmental light around the image reading apparatus such as light from an illumination arranged in a room exists when the apparatus read the document mounted on a mounting board with the image sensor.
However, if the two-dimensional image is read with the one-dimensional image sensor while scanning the document in the sub-scanning direction under the environment the document is irradiated with light of a fluorescent lamp, horizontal strips may occur in the read image due to flickers caused by the light emission by an alternating current. Thus some conventional image reading apparatuses remove such horizontal stripes of the image caused by the flickers.
For instance, in the image reading apparatus described in Japanese Patent Application Raid-open No. 10-336404, a flicker reducing circuit for increasing and decreasing the image signal is arranged by an analog circuit, and the image signal is increased and decreased by the flicker reducing circuit according to the increase and decrease of the image signal of a reference region set in a region to be read by the linear image sensor. The horizontal stripes of the image caused by the flickers are thereby removed.
However, if a unit for reducing the horizontal stripes of the image is configured by the analog circuit such as the flicker reducing circuit in Japanese Patent Application Laid-open No. 10-336404, that is, if configured by hardware, this may become a factor in complicating the configuration of the entire apparatus.